[REQUEST] Please help me build 1 tripe battle team :D

[trungsp1995]

Hello everybody. I have a Pokemon X game and I want to battle at pokemon global link rating battle - tripe, so I want everybody help me to build a team to battle. I don't know what exactly that format is : it only banned Mewtwo, Mew, Lugia, Ho-Oh, Celebi, Kyogre, Groudon, Rayquaza, Jirachi, Deoxys, Dialga, Palkia, Giratina, Phione, Manaphy, Darkrai, Shaymin, Arceus, Victini, Reshiram, Zekrom, Kyurem, Keldeo, Meloetta, Genesect, Xerneas, Yveltal, Zygarde, and Diancie , Soul Dew can't be used.
I want to build a offensive team. This is the first pokemon I have :

Sylveon (M) @ Pixie Plate
Ability: Pixilate
Level: 50
Shiny: Yes
EVs: 252 HP / 252 SpA / 4 Spe
Modest Nature
- Hyper Voice
- Calm Mind
- Psyshock
- Shadow Ball

Now I want to put a support Latias for my team. However , I don't know what item and nature should I choice for Latias ?

Latias (F)
Ability: Levitate
Level: 50
EVs: 252 HP / 4 SpD / 252 Spe
- Reflect
- Tailwind
- Light Screen
- Heal Pulse

After that , I think I should have a fire or fight pokemon to kill Steel pokemon . So I choose Volcarona. But , like Latias , I don't know what item , nature and last move should I choice for her ?

Volcarona (F)
Ability: Flame Body
Level: 50
EVs: 4 HP / 252 SpA / 252 Spe
- Heat Wave
- Quiver Dance
- Bug Buzz

And now , I need to choose 3 other pokemon ( 1 of these have mega ) . I like Gengar , Lucario , Gyarados , Gallade , Milotic , Sceptile , Aerodactyl or some pokemon with ability Intimidate ( to help sylveon and volcarona ) . However , if you see any pokemon that fit my team , suggest me :D
In conclusion , what pokemon should I choose ? With Latias, Sylveon , Volcarona , what should I fix ? Please help me :D
My English doesn't good , so please forgive me if I say something make you be confused :P
Thank you so much :D